Form-in-place foam orthopedic splint system

ABSTRACT

An apparatus and method for creating and using a lightweight custom-molded orthopedic appliance are disclosed. The orthopedic appliance is made up of an inner and an outer bladder containing components which, when combined by rupturing the inner bladder, react to form a rigid foam substance which may be conformed to the shape of the body part or surface in need of support, cushioning, or immobilization, and which quickly cures to form a firm, supportive brace for the affected body part.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to methods and apparatus for supporting orimmobilizing a body part. More specifically, the present inventionrelates to methods and apparatus for making and using a custom-fit,lightweight, durable orthopedic appliance (or “orthopedic splint”) foruse as a splint, cast, or protective pad.

2. The Relevant Technology

Many common injuries require that a body part or surface be covered witha protective dressing in order to provide support, promote healing,prevent further injury, selectively immobilize the injury, and act as ashock-absorbent buffer around it. In many such injuries, especiallywhere the hard, durable dressings currently known in the art are used,it is generally preferred that the dressing be kept in place once it hasbeen applied. This may be desired in order to preserve the precisesetting of a bone needed for proper healing, to prevent the patient frommoving or using the injured part, to enclose and protect an open wound,or to accomplish a combination of these functions.

Durable, long-lasting dressings such as these are key to medicalefficiency and treatment since they can last weeks without replacementby a doctor. This saves both the patient and the doctor significanttime, expense, and discomfort. Dressings of this type are often requiredafter accidental injuries, and may also be used after some surgicalprocedures.

Methods and devices for stabilizing body parts and surfaces facechallenges to be successful. First, since a dressing may need to be wornfor extended periods, it is preferably clean; strong; resistant to wear,degradation, and rotting, etc.; waterproof, and presentable inappearance. This helps such dressings to remain clean and sterile and toprotect the underlying skin from irritation and infection.

Since many emergency situations require the immobilization of a bodypart or surface, dressings which are quick to apply and which are strongand supportive are preferred. Further, in such emergency or first aidsituations, such dressings should be easy to apply and use, thusallowing them to be employed by untrained volunteers when no trainedmedical personnel are available.

Finally, in an era when people are embracing lifestyles of increasedphysical activity, patients demand that casts and splints leave themable to participate in as many activities as possible. As a result,lightweight, small, waterproof, and strong solutions to the castingproblem are advantageous.

Many methods and devices are currently known and relied on in the artfor stabilizing body parts or surfaces. Prime examples of these arecasts and splints including plaster casts, casts made up of syntheticresins, and splints made of resins, plastics, or metals. Many of thesematerials are easily conformable to the shape and size of the body partof the patient, and are able to strongly support the needed limb.

Plaster casts were formerly the most widely used form of casting. Inthis casting method, strips of cloth impregnated with plaster areimmersed in water and carefully wound around the affected limb inlayers. This mass is then painstakingly shaped and then allowed toharden over a period which may last hours to obtain a full set of theplaster. The result is a thick, solid, and often heavy cast amplycapable of supporting the injured limb.

Such plaster casts are useful in many applications, but also generallysuffer from disadvantages ranging from long setting periods during whichthe cast is not solid, and which may thus be more easily damaged, highweight and density, impermeability to X-rays, susceptibility to damageand weakening from exposure to water, and bulkiness.

Casts made of synthetic resins have become popular in recent years dueto their ability to harden in a shorter period of time (relative toplaster), their lighter weight and lower density (relative to plaster),their resistance to damage from water, their permeability to X-rays, andthe ability to provide them in attractive colors. These casts arepopular among wearers since they are lighter and less bulky, while stillretaining the needed characteristic of strength. The drawbacks of thistechnology include the need for wet handling and clean up or specialequipment, including in some cases, equipment for producing UV rays toharden the resins, and lesser ability to form and mold the castingmaterial.

In addition to these techniques, there is a wide range of technologiesavailable for removably splinting a wound. These technologies allow thepatient to remove the dressing when needed and replace it on their own.Many such devices involve metal or plastic supports which are pre-formedand molded within padding or foam to brace the wound. Though useful inmany applications, these devices are only very poorly adaptable to theanatomy of the user, and involve increased cost, weight, andinconvenience.

Accordingly, a need exists for a lightweight orthopedic splint applianceuseful for casting and splinting wounds which is easy to use, moldableto the anatomy of the patient, quick to harden without water applicationor external chemicals, strong, durable, waterproof, and attractive. Itwould be an advancement in the art to provide a self-containedorthopedic splint that does not require the use of water, gloves, orother accessories to enable use in the field or any other circumstance.Such a device is disclosed herein.

BRIEF SUMMARY OF THE INVENTION

The apparatus of the present invention has been developed in response tothe present state of the art, and in particular, in response to theproblems and needs in the art that have not yet been fully solved bycurrently available orthopedic splint and casting systems, includingthose referenced above.

To achieve the foregoing objects, and in accordance with the inventionas embodied and broadly described herein, a form-in-place orthopedicsplint system is provided. The orthopedic system includes an outerenvelope having an inner face and an outer face, where the inner facehas a textured surface. The outer envelope contains a liquid polyolcomposition which is in contact with this textured surface of the innerface. The inner envelope contains an isocyanate composition, and keepsthe isocyanate segregated from the polyol in the interior of the outerenvelope. This inner envelope is adapted, however, to be ruptured by auser, thus allowing the polyol and isocyanate to mix and react, causingthe formation of a polyurethane foam. The inner envelope may be rupturedby many means currently known in the art including, but not limited to,pressure, tension, physical perforation, tearing, and puncturing. Inmany forms of the instant invention, the inner and outer envelopes maybe made of a high density polyethylene or similar polymeric material.Polyethylene is notably suitable since it is an oriented plastic whichmay be easily torn in a predictable direction. Polyethylene issubstantially water impermeable, and thus prevents water from enteringthe envelopes containing the reagents. The materials used in theenvelopes should be substantially water impermeable to prevent the entryof water into the envelopes since water will react with isocyanate, thusfouling the reaction with the polyol composition. In some forms, theinner envelope is between about 2 and about 4 mils thick. In others, thehigh density polyethylene is about 2 mils thick.

In many of these embodiments of the instant invention, the outerenvelope of the orthopedic splint is shaped and configured to conform toa specific body part. Specifically, the orthopedic splint may be adaptedto conform to the hand, elbow, wrist, thumb, forearm, shoulder, foot,ankle, knee, leg, or other desired body parts. Those skilled in the artof constructing orthopedic splints and casts would be familiar with suchknown useful splint shapes, styles, and conformations.

The polyurethane foam may be adapted to have a relatively short curetime of between about 8 and 15 minutes. In some forms of the instantinvention, the polyol and isocyanate are selected to yield a curing timeof less than about 12 minutes. In a presently-preferred embodiment, thepolyol and isocyanate reagents are selected to yield a curing time ofabout 10 minutes. This amount of time is sufficient to allow a medicalprofessional to mold the cast to fit the shape of the body part orsurface to be supported, while still reducing the amount of time thatthe patient has to remain motionless and that the doctor has to spendmonitoring the patient. The exact amount of time needed for thepolyurethane foam to cure is dependent upon the polyol and isocyanatechosen, and may thus be modified or adjusted to meet a chosen cure time.

In preferred embodiments of the invention, the reagents are chosen toyield a mix/cream time of about 2 minutes. During this time, theisocyanate and polyol may be easily kneaded together and mixed. Afterthis, a rise time of approximately 4 minutes ensues in which thepolyurethane foam rises and may begin to be molded to conform to thebody part or surface to be supported, splinted, or cast. Following thisperiod, a demold period of about four minutes ensues in which thepolyurethane may still be shaped, though with more effort, and afterwhich (at about 10 minutes from disrupting the inner envelope), thepolyurethane is firm enough to provide adequate support to the bodypart. The reagents may also comprise coloring agents to give a color tothe orthopedic splint.

The thickness of the orthopedic splint system is also carefullymonitored so as to promote even strength and distribution of the foamwhile protecting the patient against exposure to uncomfortable ordangerous amounts of heat produced by the exothermic reaction involvedin the formation of the polyurethane foam.

The polyurethane foam generated within the orthopedic splint upon mixingthe polyol and isocyanate preferably has a density of between about 8and about 12 pounds per cubic foot. In a presently-preferred embodimentof the invention, the polyurethane foam has a density of about 10 poundsper cubic foot.

The foam is adapted to harden to a useful stiffness and to adhere to thetextured surface of the inner face of the inner envelope. The noveltexturing of the plastic inner face dramatically increases the surfacearea of the inner face available to the foam for bonding, and alsomechanically increases the strength of the bond formed at the interfaceof the foam and the envelope. A vast variety of textures may be usedwithin the scope of the instant invention, with those being favoredwhich maximize the surface area of the inner face. The textures are alsoconstrained by the thickness of the outer envelope, which is preferablycomprised of a high density polyethylene of between about 2 and about 4mils in thickness. Though polyethylene is preferred for the inner andouter envelopes, materials such as Mylar, polypropylene, and others withsimilar properties, may be used. In addition, though the foam of theinvention is preferably polyurethane, as described above, otherpolymeric foams which are appropriate for use with the invention may beused. The inner envelope may also be textured on its outside, or on allof its faces, and is generally comprised of a high density polyethyleneof about 2 to about 4 mils in thickness.

Additionally, in some forms of the instant invention, the inner envelopeis securely disposed at a fixed location within the outer envelope. Insome of these, the inner envelope is secured to a corner of the outerenvelope by one edge, and in others, by two edges. In others, the insideface of the outer envelope comprises part of the inner envelope. Thispredictability of location of the inner envelope makes the orthopedicsplint system of the instant invention easy to use since the location ofthe needed reagent is fixed, and it may be quickly isolated and rupturedby the user.

Further, since the inner envelopes are known to often produce astructurally weakened region in the final hardened product, it is animprovement in the art to control the location of the possible weakenedregion so as to allow that region of the system to be placed in a regionof minimum strength requirements. Indeed, in some forms of the inventionwhere the outer envelope is shaped and adapted to conform to a specificbody part, the inner envelope may be located at a position which doesnot interfere with the usefulness or strength of the resultingorthopedic splint device during the construction of the device. Further,the inner envelope may be comprised of a high-density polyethylene ofbetween 2 and 4 mils in thickness. It may, as noted above, be texturedon any or all faces to increase the strength of the bond of thepolyurethane foam material with the envelope.

The “inner envelope” may also be placed outside of the outer envelopewith a channel connecting its interior to the interior of the outerenvelope. The channel may have a seal to isolate the foam producingreagents prior to activation. This seal may be frangible such that anapplication of pressure to the inner envelope will cause the seal torupture, thus opening the channel into the outer envelope. The innerenvelope may additionally be removable from the splint after use. Thismay be accomplished by using a frangible seam to connect the innerenvelope to the outer envelope, as well as simply making it possible tosever the inner envelope with a sharp instrument.

In other forms, the instant invention comprises a method of stabilizinga body part or surface. A first step is obtaining an orthopedic splintof the instant invention as described above. This orthopedic splint willcomprise an outer envelope having an inner face with a textured surfaceand an outer face which could also be textured. The outer envelopecontains a polyol which is in contact with said textured surface of saidinner face; and the inner envelope contains an isocyanate composition.The inner envelope is adapted to be ruptured by a user, thus allowingthe polyol and composition to be mixed. A second step is the rupturingof the inner envelope and the subsequent mixing of the polyol and theisocyanate catalyst to cause the formation of a polyurethane foam. Anext step is molding the orthopedic splint device to conform to theanatomical shape of the body part or surface to be supported. Afollowing step is allowing the polyurethane foam to harden to a usefulstiffness and adhere to the textured surface of the inner face within apredetermined curing time. Factors such as the predetermined curingtime, the density of the foam, and the anatomical shape andcharacteristics of the device itself may be varied as taught hereinwithin the scope of this method.

These and other objects, features, and advantages of the presentinvention will become more fully apparent from the following descriptionand appended claims, or may be learned by the practice of the inventionas set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention of this application may be better understood by referringto the specific embodiments shown in the drawings which follow. Thedrawings depict only typical embodiments of the invention, however, andshould thus not be used to limit the scope of the invention. In thedrawings:

FIG. 1 is a top schematic view of the orthopedic splint of the instantinvention.

FIG. 2 is a top schematic view of a second form of the orthopedic splintof the instant invention.

FIG. 3 is a schematic view of a third form of the orthopedic splint ofthe instant invention.

FIG. 4 is a cross-sectional schematic view of the form of FIG. 2 at lineAA.

FIG. 5 is a cross-sectional schematic view of an form similar to thatportrayed in FIG. 2 at line AA.

FIG. 5 is a cross-sectional schematic view of another form of theorthopedic splint of the instant invention.

FIG. 6 is a cross-sectional schematic view of yet another form of theorthopedic splint of the instant invention.

FIG. 7 is a cross-sectional schematic view of still another form of theorthopedic splint of the instant invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The presently preferred embodiments of the present invention will bebest understood by reference to the drawings, wherein like parts aredesignated by like numerals throughout. It will be readily understoodthat the components of the present invention, as generally described andillustrated in the figures herein, could be arranged and designed in awide variety of different configurations. Thus, the following moredetailed description of the embodiments of the apparatus, system, andmethod of the present invention, as represented in FIGS. 1 through 4, isnot intended to limit the scope of the invention, as claimed, but ismerely representative of presently preferred embodiments of theinvention.

Definitions

Isocyanate curing agent: as used herein, the term isocyanate curingagent includes di-, tri-, and polyfunctional organic isocyanates thathave a plurality of active isocyanate functional groups and which wouldbe suitable for reacting with a polyol to form a polyurethane foam foruse in the orthopedic splint of the instant invention.

Polyol: as used herein, the term polyol connotes an alcohol containing aplurality of reactive hydroxyl functional groups.

Orthopedic splint: as used herein, the term orthopedic splint is used todenote devices which support, splint, or cast body parts or surfaces tostabilize them, immobilize them, cover them, or protect them fromfurther injury or from contamination.

Detailed Description

Referring now to attached FIG. 1, a top schematic view of a form of thefoam orthopedic splint system 10 of the instant invention is shown.Specifically, the orthopedic splint system 10 is shown comprising anouter envelope 18 and an inner envelope 14. These envelopes act aspartitions to temporarily separate the reactants needed to form apolyurethane foam.

The outer envelope 18 is uniquely adapted to provide flexibility,durability, and strength. The outer envelope is preferably constructedof a material such as polyethylene that allows flexibility in order toallow it to conform to the body part or surface. In addition, thematerial should be strong before use as a splint to safely andeffectively house the polyol needed for the reaction to formpolyurethane foam. In some embodiments the envelope is preferablycomposed of a high density polyethylene (“HDPE”) of about 16-poundstrength, and being between about 2 and about 4 mils thick. In apreferred embodiment, the high density polyethylene is about 2 milsthick. In the instant invention, the inner face of the outer envelope istextured, as is shown in FIGS. 4, 5, 6, and 7. Many advantages arerealized as a result of this unique characteristic.

First, the textured inner face of the outer envelope givesdramatically-increased adhesive strength to the bond formed between theenvelope and the polyurethane foam generated within the envelope. Thetexturing of this surface dramatically increases the surface area ofthis inner face, thus giving a much larger area for the polyurethanefoam to bond to. This significantly increases the tensile strength ofthe bond and the structural integrity of the orthopedic splint as awhole.

In certain storage scenarios, due to the fluid nature of the contents ofthe outer envelope, the polyol contents may aggregate in one area of theouter envelope, thus allowing other areas of the inner face to contacteach other. This contact may cause the inside faces to adhere to eachother—an event which would prevent proper distribution of the foamwithin the envelope, thus rendering it less useful due to uneven andimproper distribution of the foam. The texturing of the surfacepreserves the usability of the device by inhibiting opposite sides ofthe inner face from adhering to each other.

The textured surface of the inside face of the outer envelope of theinstant invention also promotes the strength of the bond by promoting“skinning” in the polyurethane. The polyurethane foam's strength and lowdensity may be attributed in part to the gas bubbles which make it afoam. If present at the interface between the foam and the envelope,however, these bubbles may weaken the bond between the foam and theenvelope by reducing the surface area at which the foam is contactingthe envelope. The surface texturing of the inside face of the outerenvelope, however, reduces this problem by promoting “skinning”—theformation of a thin polyurethane layer of up to about 1 millimeter inthickness. This polyurethane “skin” further strengthens the integrity ofthe foam/envelope bond.

The inner envelope differs from the outer envelope in that it isuniquely adapted to be ruptured so as to release the isocyanate itcontains into the reservoir of polyol contained within the outerenvelope, thus initiating the chemical reaction that forms thepolyurethane foam. This inner envelope may be adapted to be ruptured ina large variety of ways, including mechanical and chemical means. Thismay include using a seam engineered to rupture in response to a givenpressure on an edge of the envelope; an indentation, perforation, orother feature on a surface of the envelope to make it susceptible todesigned rupture; a partially cut tab on the edge of the envelope to aidin tearing; or folded forms which rupture/tear the inner envelope uponthe unfolding of the non-activated orthopedic splint. Also, the innerenvelope is preferably constructed of a durable material which resistscertain pressures in order to separate the isocyanate from the polyol.It is also further preferably constructed of a material which may beengineered to produce a seam or surface weakness (such as anindentation, perforation, etc.) which may rupture in a predictable andcontrolled manner in response to a pressure applied by a user. In somepresently-preferred embodiments, the inner envelope 14 is composed ofhigh density polyethylene (“HDPE”) of about 16-pound strength, and beingbetween about 2 and about 4 mils thick. As briefly mentioned above,polyethylene is substantially water impermeable and, being an orientedpolymer film, can be torn in a predictable fashion.

The inner envelope of the orthopedic splint device of the instantinvention may be fixed in position relative to the outer envelope. Insome forms, the inner envelope is fixed in a corner of the outerenvelope. This may involve attachment at one or more edges of the outerenvelope. This novel configuration provides benefits over the prior artby controlling the location of the inner envelope. The inner envelopemay create a weakened region in the orthopedic splint. By locating theinner envelope in a fixed position relative to the outer envelope, theinstant invention allows the user to identify and control the locationof any prospective weak spot. The orthopedic splint device may bedesigned and used to avoid putting the weakened region in a location onthe body part or surface which will be subject to strong forces whichcould cause damage to the orthopedic splint device. Additionally, theinner envelope 14 may be constructed of paraffin so as to provide aneffective vapor barrier for the isocyanates, while being convenient torupture.

FIG. 2 shows a form of the orthopedic splint device of the instantinvention in which the inner envelope 14 is mounted in a corner of theouter envelope 18. FIG. 3 shows another form of the orthopedic splintdevice 10 within the scope of the instant invention. This form comprisestwo outer envelopes 18 shown connected by a hinge region 19, which maybe constructed in many different ways familiar to one of skill in theart. One convenient method of constructing hinge region 19 is by bondingor sealing polymer sheets together to form a seam. In the form shown,the envelopes 10 are completely separate, and thus each has a separatesource of isocyanate curing agent. In the form shown in FIG. 3, oneenvelope 18 has an inner envelope 14 and the other envelope 18 hasisocyanate capsules 16. These capsules may comprise an encapsulatingagent and isocyanate curing agent. The encapsulating agent here isanalogous to the inner envelope 14 in that it segregates the isocyanatefrom the polyol, and is rupturable. The type of encapsulating agent ischosen to provide an effective vapor barrier for the isocyanate topreserve its ability to react with the polyol, and keep it separate fromthe polyol. Encapsulating agents increase the useful shelf life of theorthopedic splint of the instant invention by creating a more perfectvapor barrier to encapsulate the isocyanate. In addition, however, theencapsulating agent must be one which may be ruptured to release theencapsulated isocyanate upon activation of the device. This may beaccomplished by using methods such as manual crushing of the capsules orby using a roller. One preferred encapsulating agent is paraffin.

Embodiments such as that shown in FIG. 3 may exist in which theenvelopes are not completely separate, but only partiallycompartmentalized. Further, forms may exist within the scope of theinstant invention which comprise more than 2 outer or inner envelopesdisposed in series. Additionally, some forms of the instant inventionmay be made which comprise only one outer envelope, but multiple innerenvelopes or capsules containing isocyanate.

FIG. 4 is a schematic cross-sectional view of the embodiment of FIG. 2taken along line AA. In this view, the orthopedic splint 10 has an outerenvelope 18 with an outer face 19 and an inner face 20. The orthopedicsplint also has an inner envelope 14 with an outer surface 16 and aninner surface 17. In such embodiments, the inner and outer envelopes maybe constructed of strong, flexible materials which allow the splint tobe conformed to a body part or surface. In many embodiments of theinvention, this material is HDPE, and has a texture 40. The envelopesmay be made according to many methods known in the art, includingfolding a single sheet of material and sealing it on three sides, orsealing two pieces of material on four edges. In some forms of theinvention, the inner and outer envelopes share at least one seam. Inothers, the inner and outer envelopes may share at least two seams.

FIG. 5 shows a cross-sectional view of an embodiment in which the innerenvelope is fused on one face to an inner face 20 of the outer envelope18. In this embodiment the outer face 16 of the inner envelope 14 has atexture 40 b, similar or identical to the texture 40 a of the outerenvelope to confer the benefits discussed above to the bond between theinner envelope 14 and the polyurethane foam formed when the contents ofthe inner and outer envelopes are mixed. This embodiment furtherdemonstrates an engineered surface weakness, 15, which is constructed toretain the isocyanate during storage, but be ruptured upon theapplication of a pressure by a user to release the isocyanate.

FIG. 6 shows another cross-sectional view of an embodiment of theinstant invention 10 having an outer envelope 18 with a texture 40 andan inner envelope 19. This embodiment shows an orthopedic splintconstructed by sealing two sheets of plastic at their edges to form theouter envelope, thus creating seams 21. The inner envelope may similarlybe formed by sealing two sheets of plastic at their edges, forming seam13. In this embodiment, the inner envelope and the outer envelope shareat least one seam, as illustrated. In this embodiment, seam 17 isengineered to retain the isocyanate inside the inner envelope duringstorage, and to rupture upon the application of pressure by a user, thusreleasing the isocyanate.

FIG. 7 shows an additional cross-sectional view of an embodiment of theinstant invention 10 comprising an outer envelope 18 having an innersurface 20 with a texture 40 and an outer surface 19; and isocyanatecapsules 16. These isocyanate capsules are as defined above in referenceto FIG. 3, and comprise an encapsulating agent surrounding isocyanate.In this embodiment, as above, the invention is activated by rupturingthe individual isocyanate capsules by pressure applied by a user,including pressure applied by means including squeezing or using aroller.

The thickness of the orthopedic splint device of the instant inventionis important for a variety of different reasons. First, uniformthickness provides uniform strength and weight to the orthopedic splint,where imbalances would render some portions of the device weak, andothers heavy. Further, since the formation of polyurethane is anexothermic process, the thickness of the device is proportionate to theamount of heat given off during the polyurethane curing reaction as thedevice is molded to fit the body part or surface. Excessive heat can bumthe user or be uncomfortable. In some preferred embodiments, thetemperature of the device when the polyurethane foam is curing is lessthan about 104° F.

Orthopedic splint device thickness may be controlled by a variety ofmethods known in the art. The thickness of the orthopedic splint deviceis preferably from about 0.8 and about 1 cm. Referring now again toFIGS. 1 and 2, spot welds 22 are shown. The spot welds portrayed areexemplary of the many types of welds which may be used to regulate thethickness of the orthopedic splint when filled with foam. In addition tothis, welds may be used to partially or completely compartmentalize theouter envelope. Additionally, the shape and configuration of the outerenvelope may be altered to include features such as pleats, seams, etc.,to control the thickness of the orthopedic splint device.

The reactants contained within the inner and outer envelopes of theinstant invention are selected to keep reaction temperatures withinacceptable levels, deliver a rigid orthopedic splint product, and have acure time short enough that patients would be able to remain still andthat a medical professional would be able to attend to the curing of theorthopedic splint. Persons skilled in the polyurethane foam art arefamiliar with combinations of different polyol and isocyanate curingagent reactants that may be varied to achieve the mix/cream, rise, andde-mold times described herein. In preferred embodiments of theinvention, the reagents present in the individual envelopes are chosento yield a mix/cream time of about 2 minutes. During this time, theisocyanate and polyol may be easily kneaded together and mixed. Afterthis, a 4-minute rise time ensues in which the polyurethane foam risesand may begin to be molded to conform to the body part or surface to besupported, splinted, or cast. Following this period, a de-mold period ofabout four minutes ensues in which the polyurethane may still be shaped,though with more effort, and after which (at about 10 minutes fromdisrupting the inner envelope), the polyurethane is firm enough toprovide adequate support to the body part. The reagents may alsocomprise coloring agents to give a color to the orthopedic splint.Indeed, other chemical components which add useful properties to thepolyurethane, such as agents which improve its strength, bondingability, or molding ability, as well as components which could changethe heat output of the orthopedic splint of the instant invention, couldeasily be incorporated into the instant invention without exceeding itsscope.

In a preferred embodiment of the invention, the reactants containedwithin the inner envelope include an isocyanate curing agent. Currentlypreferred isocyanate curing agents include m-tetramethyl xylenediisocyanate (TMXDI), isophorone diisocyanate (IPDI), dimeryldiisocyanate (DDI), toluene 2,4,-diisocyanate (TDI), and4,4′-diphenylmethane diisocyanate. Persons skilled in the polyurethaneor polymeric foam art will appreciate that other isocyante curing agentsmay be used herein. In one formulation, isocyanate includes 50-75%4,4′-diphenylmethane diisocyanate in combination with a smallerpercentage of modified MDIs (“methane diisocyanates”) and otheroligomers.

Additionally, in a preferred embodiment of the invention, the reactantscontained within the outer envelope include a polyol or mixtures ofpolyols and other additives, catalysts or modifiers. In one formulation,the outer envelope contains a commercially available polyol mixture soldunder the tradename Aquathane. Aquathane generally comprises polyetherresins, polyester resins, tertiary amine catalyst, diethylene glycol,glycerine, and polyether modified siloxane. In one formulation,aquathane includes 50-95% polyether resins, 0-20% polyester resins,0.5-2.5% tertiary amine catalyst, 0-10% diethylene glycol, 0-5%glycerine, and less than 1% polyether modified siloxane. Theaquathane/isocyanate system provides a suitable polyurethane foam systemat a low cost without the requirement of chemical permits or complicatedhandling. Persons skilled in the art of polymeric foams will understandthat many reagent combinations will yield many combinations which may beused within the scope of the invention without departing from it.

The present invention may be embodied in other specific forms withoutdeparting from its structures, methods, or other essentialcharacteristics as broadly described herein and claimed hereinafter. Thedescribed embodiments are to be considered in all respects only asillustrative, and not restrictive. The scope of the invention is,therefore, indicated by the appended claims, rather than by theforegoing description. All changes that come within the meaning andrange of equivalency of the claims are to be embraced within theirscope.

What is claimed is:
 1. A method of stabilizing a body part or surfacecomprising the steps of: obtaining an orthopedic splint comprising: anouter envelope having an inner face and an outer face, wherein the innerface has a textured surface, and wherein said outer envelope contains apolyol; and an inner envelope containing isocyanate, wherein said innerenvelope is adapted to be ruptured to allow the polyol and isocyanate tobe mixed to form a polyurethane foam, and wherein said polyurethane foamhardens and adheres to said textured surface of said inner face within acuring time; and rupturing said inner envelope; mixing said polyol andsaid isocyanate to initiate a chemical reaction that causes theformation of a polyurethane foam within said outer envelope; positioningthe orthopedic splint on the body part or surface to be stabilized;molding said orthopedic splint around the contours of said body part orsurface; and allowing said polyurethane foam of said orthopedic splintto harden during said curing time.
 2. The method of claim 1, whereinsaid inner envelope is fixed by at least one point to said outerenvelope.
 3. The method of claim 1, wherein the curing time is less thanabout 12 minutes.
 4. The method of claim 1, wherein the curing time isless than about 10 minutes.
 5. The method of claim 1, wherein theorthopedic splint is adapted to conform to the specific body part orsurface to be stabilized.
 6. The method of claim 1, wherein saidpolyurethane foam has a density of between about 8 and about 12 poundsper cubic foot.
 7. The method of claim 1, wherein said polyurethane foamhas a density of about 10 pounds per cubic foot.